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The ACT Reference Catalog

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This Catalog has been superseded with the release of Tycho-2

The ACT Reference Catalog was a primary source of astrometric information
following the release of Tycho-1. In early 2000, this catalog was all
but superseded with the release of
The Tycho-2 Catalogue,
which contains 2.5 million stars compared to ACT's 1.0 million.
Copies of Tycho-2 on CD-ROM are still available
by contacting either Erik Hoeg at
Tycho-2@astro.ku.dk
or Sean Urban at
seu@pyxis.usno.navy.mil.
With that said, this webpage and its links will continue to give
information regarding the ACT Reference Catalog, even if only for
historical reasons.

Brief Description of the Catalog

The U.S. Naval Observatory has completed the compilation of the
ACT Reference Catalog, containing 988,758 stars covering the
entire sky. The motivation behind the ACT was to provide accurate proper
motions for the majority of the stars in the Tycho Catalogue (ESA SP-1200).
To do this, positions from new reductions of the
Astrographic Catalogue (AC 2000)
were combined with those of the Tycho Catalogue. The large epoch
span between the two catalogs yields proper motions about an order of
magnitude more accurate than those found in the Tycho Catalogue. The
astrometric data contained in the ACT Reference Catalog include positions,
proper motions and error estimates. These are on the Hipparcos System
(J2000.0) for epoch J2000.0. Photometric data (B and V) from Tycho are
included. Additionally, cross references to the Tycho, AC 2000, Bonner
Durchmusterung (BD), Cordoba Durchmusterung (CD), Cape Durchmusterung (CpD),
Henry Draper (HD) and Hipparcos Catalogues are given.